A study published in the April 17 edition of the journal Nature adds to the evidence debunking a recently floated theory that unsafe medical practices, and not unprotected sex, are the cause of most HIV infections in sub-Saharan Africa, Reuters Health reports. The study, conducted by researchers at the University of Oxford in England, compared the pattern of HIV's spread in Africa with the spread of hepatitis C, another bloodborne disease that is more easily passed through shared needles and contaminated blood supplies than HIV. The researchers concluded that because HIV prevalence in South Africa increased from less than 1% in 1990 to nearly 25% in 2000 while the hepatitis C rate remained steady, HIV must have been transmitted primarily through routes other than unsafe medical practices. "If the [medical practices] hypothesis were true, the epidemic history of HIV in the region should resemble that of diseases caused by bloodborne pathogens known to have only a small element of sexual transmission," the researchers wrote.

The study was launched in response to research published by eight scientists from the United States and Germany in the March issue of the International Journal of STD and AIDS that claimed that only one third of Africa's HIV infections were caused by unprotected sex and that the vast majority were linked to unsafe medical practices, such as reusing hypodermic needles. Most AIDS experts believe that about 90% of Africa's HIV infections are caused by unprotected sex.